How to Make Your Own Bonsai Soil for Healthy Bonsai

Mix bonsai soil from three parts: a water-holding grain, a porous rock and a little organic matter — for example 50% akadama or baked clay, 25% pumice or lava, 25% composted bark. Sift out the dust, keep particles 2-6 mm, and shift the ratio towards drainage in humid or monsoon conditions.

Quick facts

What you need to know	Details
All-purpose mix	50% akadama or baked/fired clay : 25% pumice or lava : 25% composted bark
Particle size	2-6 mm for most trees; 1-3 mm for shohin and mame. Sift out all dust
Ideal pH	6.0-7.0 for most species; conifers are happy slightly more acidic (5.5-6.5)
Three must-haves	Water retention, free drainage, and air spaces between particles
India-friendly substitutes	Crushed brick or terracotta grit, coarse river sand, perlite, fired clay granules, washed cocopeat, leaf mould
Never use	Plain garden soil, black cotton soil, fine builders' sand, sea sand, or pure peat/cocopeat
Monsoon adjustment	Raise porous rock to 40-50% and cut organic matter to 10-15% for the rainy months
How often to refresh	Young deciduous and tropical trees every 1-2 years; conifers and mature trees every 3-5 years, in late winter to early spring

Short on time? You can also buy our ready-made organic bonsai soil mix (1 kg) — a fast-draining blend, delivered across India.

What is Bonsai Soil?

Bonsai soil is a substrate, not soil in the garden sense. It anchors the tree, holds a working reserve of water and nutrients, and stays loose enough for air to reach the roots. It also buffers the root ball against swings in temperature and moisture.

A good mineral soil in the ground is roughly half solids, a quarter water and a quarter air by volume. Most garden soil and bagged potting soil is far too dense for a bonsai pot: it compacts, drains slowly and suffocates roots. Because a bonsai container holds so little medium, every component has to earn its place, and you top up nutrients through regular feeding rather than relying on the soil itself.

Most experienced growers settle on their own blend, and different species want different ratios. These proportions work as a reliable starting point.

Mix	Water-holding grain (akadama, Turface, fired clay)	Porous rock (pumice or lava)	Organic (composted bark, leaf mould, washed cocopeat)	India-friendly substitute
Basic all-purpose	50%	25%	25%	Baked clay granules + crushed brick grit + composted bark
Tropical species (ficus, carmona, Chinese elm, bougainvillea)	40%	25%	35%	Brick grit + coarse river sand + leaf mould or washed cocopeat
Deciduous species (maple, pomegranate, elm)	50%	30%	20%	Akadama or fired clay + perlite + composted bark
Conifers (juniper, pine, cypress)	60%	30%	10%	Fired clay + brick grit or coarse sand + a pinch of bark
Succulent types (jade, adenium)	30%	60%	10%	Coarse sand + brick grit + a little bark

Understanding what each ingredient does makes the blending much easier.

If you want a tree for an indoor spot, an indoor bonsai tree such as ficus, carmona or a Hawaiian umbrella is the easiest place to start. Check the species' light and watering needs before you choose the soil ratio, since indoor pots dry out more slowly than balcony pots.

Basic Ingredients of any Bonsai soil

Bonsai substrate is built from two families of ingredient: organic and inorganic. Before you weigh anything out, it helps to know what pH you are aiming for.

Soil pH

Soil pH runs from 0 to 14: below 7 is acidic, above 7 is alkaline. It controls how readily nutrients dissolve and become available to roots. Some nutrients are taken up more easily in acidic conditions, others in alkaline.

For most bonsai, aim for slightly acidic to neutral, around pH 6.0 to 7.0. Conifers such as juniper and pine tolerate a slightly more acidic mix, roughly 5.5 to 6.5. Where you can, match the pH the species enjoys in the wild.

One India-specific point: tap water in much of north and west India is hard and alkaline, which nudges the pot's pH upwards over time. Including some composted bark or leaf mould, and flushing the pot thoroughly when you water, helps keep it in range. Inexpensive pH strips or a probe are enough to check.

What Are the Components?

Here is what goes into the two halves of the blend.

Organic Soil Components

Organic components are dead plant materials: composted bark, leaf mould, peat and coir. They hold water and nutrients, and they are cheap and easy to find.

Their weakness is that they break down. As they decompose the particles shrink, the mix compacts, and air and drainage disappear. A soil like that does not become toxic, but airless, waterlogged conditions do lead to root rot and a weak tree. Different materials break down at different rates, so it is hard to predict exactly when.

If you want organic matter in your mix, composted pine or conifer bark is the best choice: it holds its shape for years and keeps the structure open while it lasts. Sift it so nothing smaller than 2 mm goes in. Avoid pure peat — once it dries out completely it is very hard to rewet, which leaves dry pockets inside the root ball during a Delhi or Nagpur summer.

Keep total organic content to about 10-35% depending on species, and lower it during the monsoon.

Bark

• Bark holds nutrients well and adds bulk while still letting excess water drain away.
• Fresh, uncomposted bark ties up nitrogen as it rots, which can starve the tree — use properly composted bark and feed a little more nitrogen if in doubt.
• It is mildly acidic, which suits conifers and most tropical species.

Sphagnum Moss

• Fresh sphagnum moss is an excellent rooting medium and a useful topdressing for newly collected or freshly repotted trees.
• Fresh moss keeps its structure in a pot; dried sphagnum crumbles easily, so soak it before use.
• It holds a great deal of water, so use it sparingly and only over a free-draining mix, otherwise the root ball stays sodden.
• Wear gloves when handling sphagnum and wash your hands afterwards.

Cocopeat and Leaf Mould

• Cocopeat is the practical Indian stand-in for peat: it is widely sold, rewets easily and holds moisture well.
• Buy washed and buffered cocopeat, or rinse it yourself several times — unwashed coir can be high in salts and potassium.
• Use it as 10-25% of the mix at most. On its own it compacts and stays wet.
• Well-rotted leaf mould, sifted above 2 mm, is a good free alternative if you have a garden.

Inorganic Soil Components

Inorganic components — volcanic rock, calcined and fired clays — contain little or no organic matter. They hold less water and fewer nutrients than organic material, but they are outstanding for drainage and aeration, and their low absorption gives you tighter control over feeding.

A particle-based mix lets water drain quickly and pulls fresh air into the pot after every watering. The more grit in the blend, the more aeration, and the finer and denser the root system you will build.

Akadama

• Akadama is a granular Japanese clay mined, dried, graded and bagged specifically for bonsai. It is usually sold only by bonsai nurseries and is expensive in India once shipping is added.
• It comes in grades; the harder, higher-fired grades break down more slowly than the standard product.
• It does not turn to a puddle when wet, but softens into a grainy paste.
• It is a superb substrate for Japanese maples and many broad-leaved species, and works well as part of a mix for most others.
• Used alone it can collapse into mush within one to two years, so it needs pumice or lava alongside it to keep the structure open. Akadama-heavy soils also need clearing out of the roots every two to three years, which makes them a poor choice for species that resent repeated bare-rooting.
• Fired clays are more durable than akadama and do not degrade. They can be used alone, cut with coarse sand for faster drainage, or mixed with 10-20% bark for more moisture.

Pumice

• Pumice is a soft, lightweight volcanic rock that absorbs water and nutrients without holding them too long.
• Roots cannot grow through a pumice grain, but they ramify happily around and into its soft, pitted surface.
• Over time roots abrade that surface, creating fine particles that hold the root ball snugly together.
• It is soft enough to powder if handled roughly, so sift it again before reuse.

Lava (Scoria) / Red or Black Rock

• Lava is solidified volcanic rock — essentially foamed glass, with jagged edges and partly connected pores.
• Depending on its source it carries trace minerals that plants can use.
• Roots cannot grow through lava, though they do work into the surface pores. Because the pores are poorly connected, lava takes a long soak to saturate fully, which makes it a steady, reliable drainage component.
• Root regrowth on recently collected trees planted in near-pure lava is typically vigorous.
• Its big advantage over akadama is that it can be reclaimed: dry it, sift it and use it again.

Turface and Fired Clay Granules

• Turface is calcined clay — heated hard enough to change its physical state, so the granules stay intact when soaked instead of turning to slurry.
• It is baked just enough to stabilise the particle without destroying its absorbency.
• It was developed for sports turf and golf course rootzones, where air movement is critical, and it transfers well to bonsai.
• In India, similar fired clay granules and non-clumping moler-clay cat litter are often easier to source than imported Turface. Check that the granules stay firm after a 24-hour soak before you trust them in a pot.

River Sand and Brick Grit

• Grit is simply stone particles, roughly 1.5-5 mm. Sand is the fine end, gravel the coarse end.
• Grit reduces water retention, speeds drainage and keeps the structure open. It also adds weight, which anchors the tree in the pot.
• Use coarse, washed river sand only. Avoid fine builders' sand, which sets like concrete, and sea sand, which carries salt.
• Crushed brick or broken terracotta pot, sifted to 2-5 mm and rinsed free of dust, is the most useful and affordable Indian substitute. It is fired clay, so it holds a little water, drains freely and does not break down.
• Perlite is widely available and adds aeration, but it is very light and tends to float to the surface when you water.
• Many specialists now prefer a combination of akadama, pumice and lava over plain grit where budget allows.

Soil Conditioners

The components above are only a handful of the options. Whatever you use, judge it against three criteria.

• Good water retention: the mix must hold enough water to keep the tree moist between waterings, without staying soggy.
• Good drainage: excess water must leave the pot quickly. Poorly drained soil lacks air, encourages salt build-up and leads to root rot.
• Good aeration: particles should be coarse enough to leave air pockets between them. Those pockets supply oxygen to the roots and house beneficial bacteria and mycorrhizae.

Keep those three rules in mind as you add ingredients. Whether a component is organic or inorganic matters far less than whether it delivers all three.

Right Equipment

The single most important tool is a sieve. Bagged materials arrive with dust and fines that clog air spaces, and sometimes with grass or other debris.

• A stacked sieve set (roughly 6 mm, 3 mm and 1-2 mm screens), or a kitchen flour sieve plus a mosquito-mesh frame, works perfectly well.
• Sift outdoors on a tarpaulin or old bedsheet so you can gather and store each grade.
• Coarse grade goes at the bottom of the pot as drainage, medium grade fills the pot, and the finest usable grade suits shohin and mame trees.
• Keep a scoop, a chopstick for working soil between roots, and gloves handy.
• Sift dry material. Sifting damp brick grit or bark just smears the dust back on.

Mixing Recipes

There is no single correct recipe. The blends below are starting points to adjust to your species, your pot, your climate and your watering habits.

Trust the tree rather than the recipe. If the pot stays wet for days, add more grit next time; if it dries out by midday in May, add more akadama, fired clay or bark.

Bonsai Mix Recipe

Work through these steps:

1. Sift every component dry and discard anything under 2 mm (1 mm for very small trees).
2. Rinse dusty materials such as brick grit and river sand, then let them dry.
3. Measure by volume, not weight, using the same cup or mug for each part.
4. Mix thoroughly on a sheet so the components are evenly distributed.
5. Test it: fill a pot, water it, and check that water runs out of the drainage holes within a few seconds and the mix is damp but not sodden an hour later.

Reliable starting ratios by volume:

• Tropical and subtropical (ficus, carmona, Chinese elm, bougainvillea, ixora): 4 parts akadama or fired clay, 3 parts pumice, brick grit or lava, 3 parts composted bark or washed cocopeat.
• Deciduous (maple, pomegranate, elm, wisteria): 5 parts akadama or fired clay, 3 parts pumice or lava, 2 parts composted bark.
• Conifers (juniper, pine, cypress): 6 parts akadama or fired clay, 3 parts pumice or lava, 1 part bark.
• Succulent types (jade, adenium): 3 parts fired clay, 6 parts coarse sand or brick grit, 1 part bark.

If you increase the organic portion for water retention, reduce the clay portion by the same amount so the mix does not become heavy. Avoid very fine material: root hairs struggle in a dense substrate and thicker roots cannot get enough oxygen.

Adjusting the mix for Indian seasons and regions

• Summer (March-June, north and central India): 40-45°C and dry winds empty a small pot by afternoon. Lean 5-10% more towards akadama, fired clay or bark, use a slightly finer grade, and topdress with moss. Terracotta and unglazed pots dry faster than glazed ceramic pots.
• Monsoon (June-September): this is when badly drained soil kills trees. Push the porous rock up to 40-50% and drop the organic content to 10-15%, raise pots on feet or bricks, and move shallow pots under cover during heavy spells.
• Winter (December-February, north India): growth slows and pots stay wet longer, so water only when the surface dries. Repot deciduous trees and conifers in late winter to early spring as buds swell; wait for warmer weather for tropicals.
• Coastal and southern India (Mumbai, Chennai, Kochi, Bengaluru): high humidity means slower evaporation. Favour a freer-draining, more mineral mix year round and never use sea sand.
• Balconies and rooftops: full afternoon sun and reflected heat dry pots fast — add water retention and consider a shade net in peak summer.
• Air-conditioned rooms: dry air but no sun, so soil dries from the top while staying damp below. Use a coarse, airy mix and check moisture with a chopstick before watering.

Conclusion

Making your own bonsai substrate is mostly arithmetic and sieving. Get the particle size right, keep drainage and aeration ahead of water retention, and adjust the ratio for your species and your city's weather. Your tree's health depends more on this than on almost anything else you do.

If you would rather see the idea in finished form first, look at a beautiful bonsai and note how open the surface of its soil looks. Stuck on a mix? Get in touch with Abana Homes or our contact page and we will help.

Frequently Asked Questions

Can I use normal garden soil or potting mix for bonsai?

No. Garden soil and standard potting mix are too fine and dense for a shallow bonsai pot. They compact, hold water, and starve roots of oxygen, which leads to root rot. Black cotton soil is particularly unsuitable because it swells and cracks as it wets and dries.

What can I use instead of akadama in India?

Crushed brick or terracotta grit sifted to 2-5 mm is the best low-cost substitute, as it is fired clay that holds a little water and never breaks down. Fired clay granules, non-clumping moler-clay cat litter and coarse river sand also work well in a blend.

Is cocopeat good for bonsai soil?

In small amounts, yes. Use washed, buffered cocopeat as 10-25% of the mix for tropical species that like moisture. Never use it alone: it compacts, stays wet and suffocates roots. Unwashed coir can also carry high salt levels, so rinse it thoroughly first.

What pH should bonsai soil be?

Aim for pH 6.0 to 7.0 for most species. Conifers such as juniper and pine tolerate slightly more acidic conditions around 5.5 to 6.5. Hard, alkaline tap water gradually raises pot pH, so include some composted bark and flush the pot thoroughly when you water.

How often should I change my bonsai soil?

Repot young deciduous and tropical trees every one to two years, and mature trees or conifers every three to five years. Akadama-heavy mixes break down faster and need clearing from the roots every two to three years. Late winter to early spring, as buds swell, is the best window.

Why does water sit on top of my bonsai soil?

The mix has too many fine particles or too much decomposed organic matter, so the surface has sealed. Scratch the top layer open as a short-term fix, then repot into a sifted, mineral-heavy blend. If water instead runs straight through, the mix needs more akadama, fired clay or bark.

Do I need to sterilise homemade bonsai soil?

Not usually. Sifting and rinsing removes most dust and debris, and mineral components carry little disease risk. If you are reusing old substrate or adding garden leaf mould, dry it fully in the sun and sift it again before mixing.

Is the same mix suitable for indoor and outdoor bonsai?

The ingredients are the same, but indoor pots dry more slowly, so use a slightly coarser, airier blend with a little less organic matter. Outdoor trees in full sun on a balcony or rooftop need more water retention, particularly through the north Indian summer.

Sources

• Royal Horticultural Society (RHS) plant advice: https://www.rhs.org.uk/advice